Compounds which release a photographically useful group through oxidation and reduction reaction are known.
For example, hydroquinone derivatives which release a development restrainer are disclosed in U.S. Pat. Nos. 3,379,529, 3,620,746, 4,144,071, 4,377,634, 4,332,878, 3,930,863 and the like. Furthermore, catechol derivatives which release a development restrainer are disclosed in British Pat. No. 1,400,149.
As described in the above-described patents, conventional compounds have been used for various purposes depending upon the type of light-sensitive material. Among those compounds, hydroquinones which release a development restrainer are effective for the purpose of improving sharpness, graininess, and color reproduction in color photographic light-sensitive material. However, with the recent demand for improved photographic properties, conventional compounds are no longer satisfactory.
Furthermore, there has been a need for a compound which improves dot quality in silver halide photographic material which undergoes a photomechanical process.
Still further, there is a need for a material to improve sharpness in black-and-white photographic light-sensitive material used for X-ray photography.
The above-described conventional and well known compounds fall short of the above-described objectives because they are readily oxidized and immediately release a development restrainer upon development. Those compounds are extremely unstable and are oxidized by air during storage of the light-sensitive materials in which they have been incorporated.
U.S. Pat. No. 4,476,219 discloses gallic acid amides which improve graininess to some extent, but are not satisfactory and additional improvement is necessary.